EP3993562A1 - Cartouche chauffante comportant une pâte de remplissage céramique - Google Patents

Cartouche chauffante comportant une pâte de remplissage céramique Download PDF

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Publication number
EP3993562A1
EP3993562A1 EP21205225.2A EP21205225A EP3993562A1 EP 3993562 A1 EP3993562 A1 EP 3993562A1 EP 21205225 A EP21205225 A EP 21205225A EP 3993562 A1 EP3993562 A1 EP 3993562A1
Authority
EP
European Patent Office
Prior art keywords
heating
ceramic
metal sleeve
cartridge according
heating coil
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP21205225.2A
Other languages
German (de)
English (en)
Inventor
Patrick Le Coent
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Eichenauer Heizelemente GmbH and Co KG
Original Assignee
Eichenauer Heizelemente GmbH and Co KG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Eichenauer Heizelemente GmbH and Co KG filed Critical Eichenauer Heizelemente GmbH and Co KG
Publication of EP3993562A1 publication Critical patent/EP3993562A1/fr
Pending legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/40—Heating elements having the shape of rods or tubes
    • H05B3/42—Heating elements having the shape of rods or tubes non-flexible
    • H05B3/48—Heating elements having the shape of rods or tubes non-flexible heating conductor embedded in insulating material
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B2203/00—Aspects relating to Ohmic resistive heating covered by group H05B3/00
    • H05B2203/014—Heaters using resistive wires or cables not provided for in H05B3/54

Definitions

  • the invention relates to a heating cartridge, in particular for heating a spray nozzle.
  • Such heating cartridges contain a heating wire which is arranged as a heating coil in a metal sleeve.
  • a heating cartridge which has a continuous central fitting bore for receiving a plastic injection nozzle.
  • This cartridge heater has an annular interior that is enclosed by a metal jacket.
  • a heating coil which is wound onto a ceramic winding body, is embedded in ceramic powder in this interior space.
  • the metal jacket is assembled from two parts, between which there is a gap enclosed by an annular wall. All parts are compressed together by radial pressing.
  • the annular wall forms a bead on the outer metal jacket, from which the connections of the heating coil are led out and which is filled with casting compound or insulating granules.
  • Cartridge heaters for spray nozzles and other applications must be compact and enable high heat outputs, which requires good thermal coupling of the heating coil to the surrounding metal sleeve.
  • the interior of the metal sleeve is therefore usually filled with ceramic powder such as magnesium oxide and the metal sleeve is then plastically deformed, with the ceramic powder being compacted.
  • the outside of the metal sleeve often has to be reworked, in particular ground down.
  • not all metal sleeves are suitable for this procedure.
  • the metal sleeve may have a shape, material, thickness, or coating unsuitable for compaction.
  • the process is very complex.
  • the metal sleeve in which the heating coil is arranged is filled with ceramic casting compound.
  • a space between a ceramic core, which surrounds the heating coil, and the inside of the metal sleeve is therefore filled with ceramic casting compound. Since a ceramic casting compound is filled into the metal sleeve as a liquid, post-compacting by plastic deformation of the metal sleeve can be dispensed with. Post-processing of the outside of the metal sleeve is therefore not necessary.
  • the heating coil can therefore easily be wound around a ceramic core containing one or more channels contains, in which, for example, a lead of the heating coil is arranged. It is also possible to initially insert the heating coil into the metal sleeve without a core and then to fill the interior of the metal sleeve with ceramic casting compound. In this way, the ceramic casting compound then forms a ceramic core, which the heating coil surrounds and also fills the space between the core and the inside of the metal sleeve.
  • the ceramic core is preferably designed in one piece, for example through the casting compound or as a separate component. However, individual segments such as discs that are joined together are also conceivable.
  • a temperature sensor can be arranged directly in the potting compound, which conducts heat very well, since no mechanical pressure is exerted on it.
  • a protective housing can therefore be dispensed with.
  • a very precise temperature measurement can advantageously take place in this way.
  • the temperature sensor is preferably arranged between a bottom of the metal sleeve and the ceramic core in order to measure the temperature directly at the spray opening. Its connections can be routed together in one or separately in two channels of the ceramic core. However, it is also possible to arrange at least one temperature sensor itself in a channel, in particular in the center of a channel, of the ceramic core.
  • the heating cartridge also has several temperature sensors, e.g. to record both the temperature at the spray nozzle and inside the ceramic core.
  • the metal sleeve can have a helical flow channel on its outside.
  • Flow channels can extend around the metal sleeve like a thread and—if the heating cartridge is inserted into a spray nozzle—specify the flow path of a liquid to be heated, so that heat generated by the heating cartridge is absorbed well.
  • a metal helix can also be arranged on the outside of the metal sleeve. Together with the outside of the metal sleeve and the inside of a housing of the spray nozzle, this can also specify a helical flow path for a liquid to be heated. If a flow channel is present, this can be located, for example, in a cylindrical portion of the metal sleeve.
  • Such a flow channel can be formed by one or more grooves on the outside of the metal sleeve. Grooves can also be provided on the outside of the metal sleeve in order to increase the surface area and thus improve heat dissipation. For this purpose, grooves can be provided which run in the longitudinal direction of the metal sleeve and whose side walls are designed as ribs.
  • the ceramic casting compound preferably contains aluminum oxide, magnesium oxide or aluminum nitride as a component, in particular as a main component.
  • the casting compound can contain a binder, for example silicone resin, as a further component. Water-soluble silicone resins are preferred as binders. Using a binder increases moisture resistance.
  • the casting compound can advantageously be mixed with water before use. After casting the metal sleeve, the casting compound can be dried and hardened by the action of temperature.
  • Potting compounds are preferably used which have a thermal conductivity of at least 15 W/mK, preferably at least 30 W/mK. Casting compounds with a viscosity of at least 11000 mPas, in particular at least 15000 mPas, are also preferred.
  • the potting compound advantageously has a volume resistance of at least 10 9 ohms/cm at room temperature, preferably at least 10 13 ohms/cm at room temperature, in order to ensure electrical safety.
  • a value of at least 5 ⁇ 10 -6 /K is advantageous as the coefficient of thermal expansion in order to prevent the formation of a gap on the inner wall of the metal sleeve.
  • a spacer preferably made of ceramic, is arranged between the heating coil and the inside of the metal sleeve.
  • the spacer can, for example, be ring-shaped or sleeve-shaped.
  • partial ring-shaped spacers are preferred, that is to say spacers which only bear against part of the circumference of the heating coil.
  • Several partially ring-shaped spacers, which are in contact with different circumferential sections of the heating coil, can together center the heating coil in a coil area.
  • the spacers can have a projection pointing radially inward, which sits between adjacent turns of the heating coil, for example is clamped there.
  • the number of spacers can be varied, for example two, three or more spacer areas can be provided in which two or more spacers each lie against a peripheral section of the heating coil.
  • Spacers are particularly advantageous if the heating coil is initially inserted into the metal sleeve without a core and the interior of the metal sleeve is then filled with ceramic casting compound in order to form the core.
  • a spacer or a plurality of spacers can stabilize the heating coil when the casting compound is poured in.
  • the axial extent of the spacers is preferably one to two times the coil pitch, ie the distance from one turn of the heating coil to the adjacent turn, measured from wire center to wire center.
  • the spray nozzle shown can be used, for example, to heat or vaporize reducing agent before it is introduced into the exhaust system of a motor vehicle.
  • the spray nozzle has a housing 1 with a spray opening 2, a connection 3 for the electrical lines and a connection 4 for liquid.
  • a heating cartridge 10 is arranged in the Figures 2 to 4 is shown and explained in more detail below.
  • the heating cartridge 10 has a ceramic core 11, a heating coil 12 consisting of one or more heating wires which is wound around the ceramic core 11, and a metal sleeve 13 in which the ceramic core 11 and the heating coil 12 are arranged.
  • the interior of the metal sleeve 13 is cast with a ceramic casting compound.
  • the space between the heating coil 12 and the inside of the metal sleeve 13 is therefore filled with ceramic casting compound, preferably over the entire length of the heating coil 12, so that good thermal coupling of the heating coil 12 to the metal sleeve 13 results.
  • the ceramic casting compound is filled into the metal sleeve 13 as a pasty liquid and consists predominantly of aluminum oxide, magnesium oxide or aluminum nitride.
  • the ceramic casting compound can also contain silicon oxide and, in particular when it is filled in, also water and/or a binder, for example a silicone resin. Both water-insoluble and water-soluble silicone resins are suitable.
  • the ceramic casting compound is dried and hardened by heat treatment. Any binder initially present can burn in the process.
  • the ceramic core 11 contains a plurality of channels 6.
  • a connection section 14 of the heating wire, which also forms the heating coil 12, runs in one of these channels 6.
  • Connecting lines 9 of a temperature sensor 15, which is arranged between a base 16 of the metal sleeve 13 and the ceramic core 11, run in two other channels 6.
  • the temperature sensor 15 can, for example, be an electrical resistor, such as an NTC resistor.
  • the connecting lines 9 can also be combined in a common channel 6 run.
  • the ceramic core 11 can contain one or more additional channels 6 in which no lines run. These additional channels 6 are filled with ceramic casting compound, but they can also be empty.
  • the ceramic core 11 can consist of ceramic disks stacked on top of one another.
  • the metal sleeve 13 has a cylindrical section with an external thread. In this way, a helical flow channel 17 is formed on the outside of the metal sleeve 13 .
  • a helical flow channel ensures that the liquid to be heated in the spray nozzle is guided along a helical path along the heating cartridge 10 and can therefore easily absorb heat from the heating cartridge 10 .
  • the end of the heating coil 12 facing the bottom 16 of the metal sleeve 13 is surrounded by a ceramic ring or a ceramic sleeve 18 .
  • the heating coil 12 can be fitted with a ceramic ring or a ceramic sleeve 18 their bottom end are advantageously supported.
  • the ceramic ring or the ceramic sleeve 18 therefore preferably has at its bottom end a radially inwardly projecting annular shoulder for supporting the heating coil 12, while a cylindrical side wall of the ceramic ring or the ceramic sleeve 18 centers the heating coil 12.
  • a further function arises in relation to the temperature element 15. As the ceramic sleeve 18 increases the distance between the ceramic core 11 and the base 16 of the metal sleeve with its annular shoulder, it creates space for the arrangement of a temperature sensor 9.
  • the ceramic ring or the ceramic sleeve 18 thus surrounds an end section of the ceramic core 11 or the heating coil 12 and can be supported on the bottom 16 of the metal sleeve 13 .
  • the ceramic ring or the ceramic sleeve 18 can be provided with slits or openings so that the ceramic potting compound can more easily fill all cavities in the heating cartridge 10 .
  • a ceramic bushing 19 centers the ceramic core 11 at the upper end.
  • the potting compound is preferably dimensioned such that the entire heating wire with heating coil 12 and heating wire connections 14 is embedded in the potting compound. In the present example, at least part of the interior of the head sleeve 21 is therefore also filled with the casting compound, in particular at least to the extent that the heating wire connections 14 are completely embedded therein.
  • FIG 5 shows another exemplary embodiment of a heating cartridge 10 for a spray nozzle according to FIG 1 .
  • the ceramic core around which the heating coil 12 is arranged, is made of casting compound.
  • the ceramic core is therefore not a separate component here that is inserted into the metal sleeve 13 together with the heating coil 12 .
  • the heating coil 12 is initially inserted into the metal sleeve 13 without a core and then the interior of the metal sleeve 13 is filled with ceramic casting compound.
  • the ceramic casting compound then forms a ceramic core, which the heating coil 12 surrounds and also fills the space between the core and the inside of the metal sleeve 13 .
  • spacers 24 are provided along the heating coil 12 between the end regions, in addition to centering aids or spacers in the end region, as represented by the ceramic sleeve 18 and the ceramic bushing 19, which surround the heating coil 12.
  • the heating coil 12 is shown together with spacers 24 .
  • 7 shows spacer 24 in a detailed view.
  • the spacers 24 are made of ceramic and are partially ring-shaped, for example. In the exemplary embodiment shown, two almost semicircular spacers 24 support the heating coil 12 in all directions along one turn. However, other spacers are also conceivable, which extend completely around the heating coil 12 or around more or less than half the circumference of the heating coil 12. In the exemplary embodiment, the spacers 24 each have a contact surface 26 which is in contact with the inside of the metal sleeve 13 stands. However, just a linear or multi-point contact is also conceivable.
  • the spacers 24 can have one or more radially inwardly directed projections 25, for example in the form of an annular bead, which protrude between adjacent windings of the heating coil 12 and thus prevent or at least make it more difficult for the spacers 24 to move axially when pouring in sealing compound.
  • the projections 25 can also be thickened at their ends, so that they form a latching function and are fixed between the windings during assembly, which greatly facilitates assembly. If the spacers 24 have projections 25, they usually follow the course of the winding.
  • the spacers 24 are therefore not aligned exactly on a radial plane, but are slightly inclined thereto, so that individual sections of the spacers 24 are not directly radially opposite one another.
  • the Figures 6 and 7 show enlarged partial views figure 5 , in which only the heating coil 12 with spacer 24 or only the spacer 24 are shown. This trend is clearly visible in it.
  • the contact surface 26 in the example thus has an axial displacement along the circumference corresponding to the helix height. This would also be the case with only linear or even multi-point support between the spacer 24 and the inside of the metal sleeve 13 .
  • the version shown also has a guide 27 for guiding the temperature sensor (in figure 5 not shown) on.
  • this has a base part adapted to the ceramic sleeve 18 with a central opening for the temperature sensor and a tubular section for guidance the electrical supply line to the temperature sensor.
  • the guide aid 27 can also be made in one piece with the ceramic sleeve 18 .
  • FIG. 8 and 9 another exemplary embodiment of a heating cartridge 10 is shown. Like the sectional view of the 9 shows, the internal structure of the heating cartridge 10 essentially corresponds to the embodiment of FIG figure 5 .
  • a heating coil 12 is arranged in the metal sleeve 13 and the interior of the metal sleeve is filled with ceramic casting compound.
  • the potting compound thus forms a ceramic core around which the heating coil 12 is arranged and fills the space between the core and the inside of the metal sleeve 13 .
  • the heating coil 12 is when filling the potting compound by spacers 24, as in the Figures 6 and 7 are shown, and stabilized by a ceramic sleeve 18 into which one end of the heating coil 12 protrudes.
  • the difference from the exemplary embodiments described above consists essentially only in the design of the outside of the metal sleeve 13. How 8 shows, the metal sleeve 13 of this heating cartridge 10 on its outside in the longitudinal direction running grooves, the side walls are formed as ribs 28 and thus improve the heat dissipation.
  • the side walls are formed as ribs 28 and thus improve the heat dissipation.
  • other configurations of grooves and ribs for example running transversely, are also conceivable.
  • a separate head sleeve has also been dispensed with in this exemplary embodiment, i.e. the head sleeve is an integral part of the metal sleeve 13.
  • the in the figures 8 and 9 The heating cartridge 10 shown can be used, for example, for a hydrogen tank in fuel cell technology or hydrogen combustion. A pressure of up to 600 bar can occur in such tanks. Since the heating cartridge 10 was filled with ceramic casting compound and thus contains no cavities, compression or deformation of the metal sleeve 13 due to static pressure of a few hundred bar is practically impossible, so that the heating cartridge 10 can easily withstand such pressure loads.

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  • Resistance Heating (AREA)
EP21205225.2A 2020-10-30 2021-10-28 Cartouche chauffante comportant une pâte de remplissage céramique Pending EP3993562A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102020128588 2020-10-30
DE102020132008 2020-12-02

Publications (1)

Publication Number Publication Date
EP3993562A1 true EP3993562A1 (fr) 2022-05-04

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ID=80857407

Family Applications (1)

Application Number Title Priority Date Filing Date
EP21205225.2A Pending EP3993562A1 (fr) 2020-10-30 2021-10-28 Cartouche chauffante comportant une pâte de remplissage céramique

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2625714A (en) * 2022-12-06 2024-07-03 Thermo Fisher Scient Bremen Gmbh A cartridge for a cartridge heater

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2831951A (en) * 1954-07-06 1958-04-22 Watlow Electric Mfg Cartridge heater and method of making same
US3970822A (en) * 1975-03-17 1976-07-20 Watlow Electric Manufacturing Company Electric cartridge heater
US6408503B1 (en) * 1999-03-18 2002-06-25 Hotset Heizpatronen U. Zubehor Gmbh Method of making injection-molder heating element
DE202007010865U1 (de) 2007-08-03 2007-10-11 Türk & Hillinger GmbH Elektrische Heizpatrone
FR3028708A3 (fr) * 2014-11-14 2016-05-20 Rotfil Srl Cartouche chauffante pour radiateur electrique
US10728956B2 (en) * 2015-05-29 2020-07-28 Watlow Electric Manufacturing Company Resistive heater with temperature sensing power pins

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2831951A (en) * 1954-07-06 1958-04-22 Watlow Electric Mfg Cartridge heater and method of making same
US3970822A (en) * 1975-03-17 1976-07-20 Watlow Electric Manufacturing Company Electric cartridge heater
US6408503B1 (en) * 1999-03-18 2002-06-25 Hotset Heizpatronen U. Zubehor Gmbh Method of making injection-molder heating element
DE202007010865U1 (de) 2007-08-03 2007-10-11 Türk & Hillinger GmbH Elektrische Heizpatrone
FR3028708A3 (fr) * 2014-11-14 2016-05-20 Rotfil Srl Cartouche chauffante pour radiateur electrique
US10728956B2 (en) * 2015-05-29 2020-07-28 Watlow Electric Manufacturing Company Resistive heater with temperature sensing power pins

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2625714A (en) * 2022-12-06 2024-07-03 Thermo Fisher Scient Bremen Gmbh A cartridge for a cartridge heater

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